1. Field of the Invention
This invention relates to a marking apparatus and more particularly to apparatus that supports marking elements for vertical and lateral movement into and out of marking position with respect to the surface of a plate member to be marked.
2. Description of the Prior Art
Conventional plate marking and stamping machines impress identification marks on the surface of plates, slabs, billets and the like as they travel on a roller table during the production process for the purpose of identifying the plate by the impression made. The stamps or marking elements impact the surface of the plate as it advances on the roller table in marking relationship with the stamp or marking elements. In this manner a continuous marking process is accomplished as the plate in the production process is transferred from station to station without requiring separate handling of the plate for marking purposes.
As the roller table advances the plate into marking position with respect to the stamping machine, the marking stamp or heads are urged by a power means to strike the surface of the plate with sufficient force and velocity to impress a mark on the plate. The stamp is returned by the marking means to its original position. A problem is created by the need to replace the stamps or marking elements in the support member requiring interruption of the plate feeding on the roller table. Furthermore, substantial production time is lost in the interchange of the marking elements on the marking head.
One method of changing stamps in marking slabs is disclosed in U.S. Pat. No. 2,690,116 wherein a group of stamps are retained by a stamp retaining member. A hammer is provided for each stamp and by actuating a pneumatic piston cylinder assembly the selected hammer is swung down to strike the corresponding stamp retained by the stamp retaining member. The piston cylinder assembly is also operable to provide for simultaneous release of all the hammers so that the slab is marked by all of the stamps. To change a stamp in the stamp retaining member the stamp releasing member is manually raised for removal of the stamp and insertion of a new stamp in the vacant slot. With this arrangement, if a single stamp is to be impressed upon the slab, the position of the impression is limited to the position of the respective stamp in the stamp retaining member relative to the surface of the slab. Furthermore, the arrangement of the stamps made on the slab is determined by the arrangement of the stamps in the retaining member and the position of the stamp retaining member relative to the surface of the slab.
In U.S. Pat. No. 3,020,834 a changeable stamping head is disclosed as being mounted by a carrying frame and moved between a stamping position and an indexing position displaced from the stamping area for setting the stamping dies in a selected position for the next stamping operation. Consequently, with this arrangement, to facilitate a change of dies in the stamping head, the stamping head must be removed from stamping relation with the surface of the object to be marked.
There is need for an apparatus for the marking and stamping of plates supported on a roller table which permits selective positioning of marking elements relative to the surface of the plate when the marking element holder is positioned to strike the surface of the plate. While it has been suggested to provide for changeable marking elements in the marking element holder, the prior art systems require moving the marking element holder from marking position with respect to the plate or manually removing the stamps from a stamp holder and replacing them with new stamps.